Brazilian federal police said Friday they were carrying out 33 search warrants and 11 detention warrants in the Operation Carwash anti-graft investigation, including two in Sao Bernardo do Campo, the hometown of fomer President Luiz Inacio Lula da Silva, Reuters reported.

Police picked up Lula at his home on the outskirts of Sao Paulo and released him after three hours of questioning.

Local media reported that the search warrants against Lula's properties were issued based on allegations that the former head-of-state had received benefits-in-kind from construction firms implicated in the Petrobras scandal.

The arrest follows a news reports published on Thursday which included a written testimony from Delcídio do Amaral, a senator in the Workers' Party, who accused ex President Lula of bribery.

Meanwhile, the recently resigned justice minister José Eduardo Cardozo delivered a press conference yesterday afternoon disputing many of Do Amaral's claims, questioning the credibility of a politician who is being prosecuted and facing expulsion from the party and the loss of his Senate seat.